This is a competing continuation proposal for Years 23-28 of the Health and Retirement Study (HRS) cooperative agreement, in response to NIA RFA #AG-12-001. We propose to continue core data collection on the steady-state design laid out in the two previous renewal cycles, and collect biomarkers and measures of physical performance in in-person interviews on the rotating half-sample design established in the previous cycle. HRS provides a uniquely rich, nationally representative longitudinal dataset for the community of scientific and policy researchers who study the health, economics and demography of aging. It provides a research data base that can simultaneously support cross-sectional descriptions of the U.S. population over the age of fifty, longitudinal studies of a given cohort over a substantia period of time and research on cross-cohort trends. The HRS project creates a data system extending beyond the core survey data. One component of this extended data system consists of linkages to administrative data, including Social Security earnings and benefit records, Medicare utilization and diagnostic records, employer pension records, and the National Death Index. We plan to expand these linkages to include Medicaid records, links to Veteran's Administration data, and information on nursing home residents from the Minimum Data Set. Another component is genome-wide genotyping data from consenting respondents that will be available in dbGaP by the start of this next renewal cycle. The HRS provides public use data designed to allow the full power and creativity of America's scientific community to address the challenges of an aging population. The HRS is making a significant impact on research on aging through investigator-initiated research which uses the HRS as an input without charge to researchers or granting agencies. Over 1,000 peer-reviewed journal publications by over 1,000 different authors and co-authors and over 200 doctoral dissertations have appeared based on the HRS.